1. Field of the Invention
The present invention relates to novel compositions of matter useful as binders for powder paints, and, more especially, to such compositions comprising an epoxy resin and a cross-linking agent which comprises a certain dianhydride bearing ester functions.
2. Description of the Prior Art
In the U.S. Pat. No. 4,024,111 to Thomas et al., and copending application for reissue, Ser. No. 885,107, filed Mar. 9, 1978, both assigned to the assignee hereof and both hereby expressly incorporated by reference in their entireties and relied upon, there is described a certain cross-linking agent comprising a dianhydride with ester functions, said cross-linking agent being the product of the reaction between trimellitic anhydride and a diol, at elevated temperatures, and wherein such reaction the molar ratio of the trimellitic anhydride to the diol is not in excess of two, and preferably is between 2/1 and 2/1.5. Compositions comprised of such cross-linking agent and a saturated polyester having terminal hydroxy groups are eminently well suited as binders for powder paints.